“As the instrument scientist for NASA’s SPHEREx mission, which aims to measure the near-infrared spectra of around 450 million galaxies, my work involves determining what we need to build to capture data from space, using a combination of engineering, cosmology and astrophysics skills. Here in my laboratory at the California Institute of Technology in Pasadena, we’re calibrating a telescope that will survey hundreds of millions of galaxies. We need a snappy name: SPHEREx stands for the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer.
To do these analyses, we’ve built a large cryogenic optical testing facility to simulate the conditions that the spacecraft will be working in. The lab has a gold-coated, sapphire window, which you can see behind me in this photograph. Unlike glass, sapphire is clear in the infrared range, and this helps us to control how much light goes in and out of the room.
The telescope that we’re calibrating right now will be sent into space early next year and, if all goes well, it will capture images for two years. We’re trying to measure a signal that was emanated for fractions of a second after the Big Bang. The spacecraft will stay in space for 25 years; it will then return to Earth and burn up in the atmosphere.
This instrument will operate at ridiculously cold temperatures, so it’s essential that we do our measurements under the same conditions. We shake it around to make sure it can withstand being launched into space.
SPHEREx is a mission set up to survey the entire sky, spectroscopically. We’re not just taking images but aiming to separate out every pixel of the entire celestial sphere.
One of the best things about my job is physically building something that will allow us to ask grand existential questions. That we can make these precision instruments to measure something that can seem so abstract is phenomenal.”
